Ellipse template



July 31, 1962 E. A. FuEss 3,046,660

ELLIPSE TEMPLATE Filed Nov. 21, 1960 YISOMETRIC XIS INVEN'fOR.

EUGENE A. FUESS BY Maia-m United States Patent @fifiee 3,046,660 ELLIPSETEMPLATE Eugene A. Fuess, San Diego, Calif. (439A W. Earll Drive,Scottsdaie, Ariz.) Filed Nov. 21, 1960, Ser. No. 70,720 2 Claims. (Cl.33-1) The present invention relates generally to drafting instrumentsand more particularly to an ellipse template.

The primary object of this invention is to provide an ellipse templatewith a logarithmically curved guide edge to fit various sizes ofellipses and having means to locate two further points in each quadrantof an ellipse when a first point is known, the guide edge then beingplaced to join the three resultant points to obtain the curve for onequadrant of an ellipse.

Another object of this invention is to provide an ellipse guide which isparticularly suitable for drawing isometric ellipses, a scribed linebeing used as an isometric axis reference and a pair of slots tofacilitate marking the major and minor axis radii, the reference lineand slots being located with respect to a common center at distanceproportional to their respective radii.

A further object of this invention is to provide an ellipse templateadaptable to drawing ellipses at various specific angles where onidentifiable radius is known, two other radii being easily located todefine the required curve.

Still another object of this invention is to provide an ellipse templatewhich can be used without the need for reference to any tables orscales, the guide means being incorporated into a single piece oftransparent plastic material which serves as the sole instrument.

Finally, it is an object to provide an ellipse template of theaforementioned character which is simple and convenient to manufactureand use and which will give generally efiicient and durable service. I

With these and other objects definitely in view, this invention consistsin the novel construction, combination and arrangement of elements andportions, as will be hereinafter fully described in the specification,particularly pointed out in the claims, and illustrated in the drawingwhich forms a material part of this disclosure, and in which:

FIGURE 1 is a plan view of the template for drawing isometric ellipses;

FIGURE 2 is a sectional view taken on the line 2-2 of FIGURE 1;

FIGURE 3 is a diagrammatic view of the template on a reduced scale,showing the method of obtaining the required radii; I

FIGURE 4 is a diagrammatic view showing the method of drawing theellipse quadrants; and

FIGURE 5 is a plan view of an ellipse template for drawing ellipsesother than isometric.

Similar characters of reference indicate similar or identical elementsand portions throughout the specification and throughout the views ofthe drawing.

The template, generally indicated at 10, is made from a fiat sheet oftransparent plastic material for maximum visibility and has a curvedguide edge 12 of logarithmic spiral form, which is elfectively acomposite curve to fit the range of ellipses capable of being drawn withthe template.

This particular curve of progressively increasing radius is well knownas a guide for drawing various sizes of ellipses with different portionsof the curve and no claim is made to the use of such a curve in itself.The mathematical equation for plotting the curve is related to the angleof rotation of the circle represented by the ellipse, the curved edge 12being that used to draw isometric ellipses. For convenience, thetemplate has a straight base edge 14 and a vertical edge 16 tofacilitate its use with a T-square, drafting machine, or other suchinstrui meats.

Adjacent the intersection of the edges 14 and 16 is a center point 18marked by a pair of crossed center lines 20 inscribed in the template,the center point being the starting reference for drawing any ellipse.Scribed across the template 1!? is a linear visual reference elementwhich may take the form of an isometric axis reference line 22, whichmay be in any convenient position on the template. The reference line22' is illustrated as straight, but may be curved according to the spaceavailable, the critical factors being that the point on the referenceline nearest the center point 18 is spaced from thecenter point at adistance equal to the isometric radius of the smallest ellipse which canbe accurately drawn with the curved edge 12. Similarly, the point on thereference line22 furthest from the center point 18' is spaced at adistance equal to the isometric radius of the largest ellipse which canbe drawn with the template. Between these points the line can take anyform within reason and a slight extension may be provided on each end ofthe line for practical purposes.

On the side of the reference line 22 remote from the center point 18 isa major axis slot 24 having a guide edge 26 and on the other side ofsaid reference line is a minor axis 'slot 28 having a guide edge 30. Theguide edges 26 and 30 conform to the delineation of the reference line22 and are spaced therefrom in correspondence with the ratio of themajor and minor radii of an ellipse relative to the isometric radius.The ratio of the isometric'radius to the major and minor radii is adefinite figure and the guide edges 26 and 3t can be positively locatedrelative to the reference line. Thus by projecting a line from thecenter point 18 to intersect the reference line 22 and guide edges 26and 30, it will be found that the points of intersection represent theisometric radius'and the major and minor radii, respectively, of aspecific ellipse.

' The first steps in drawing an ellipse are illustrated in FIGURE 3. Themajor axis 32 and minor axis 34 are drawn from a center in the requiredlocation, together with the isometric axis 36 which, in isometricprojection, is at an angle of 30 degrees to the major axis. The

isometric radius is normally the one known factor when drawing anisometric ellipse and this radius is marked off along the isometric axis36 to provde a point A. The

template It) is then placed over the drawing with the center point 18over the intersection of the drawn axes and is rotated until thereference line 22- passes through point A. The intersections of theisometric axis 36 with guide edges 26 and '30 are then marked to providepoints B and C, respectively.

With reference now to FIGURE 4 of the drawing, from the ellipse centerindicated at 0, an arc of radius OB is drawn across the major axis 32 tolocate the major radius point X, and an arc of radius 00 is drawn acrossthe minor axis 34 to locate the minor radius point Y. The template 10 isthen placed over the drawing and adjusted until the curved edge 12connects the three points XAY accurately, the line being drawn in toprovide one quadrant of the ellipse. The various axes can be extendedand the radii marked off for the other quadrants of the ellipse, thetemplate being moved around to draw the.

remaining quadrants, as indicated in dash line in FIG- URE 4.

Thus by knowing the isometric radius of the required ellipse, anyisometric ellipse can be drawn, within the dimensional limits of thetemplate, without the need for sealing any other measurements orreferring to special tables. Portions or complete ellipses may be drawnas desired.

By way of illustrating the application to ellipses other Patented July31, 1962 I than isometric, a modified template 40 is shown in FIG- URE5, this template having a curved edge 42 of the appropriate logarithmiccurve. In drawing ellipses other than isometric, the major radius is theknown factor and the template 40 is provided with a reference slot 44having a guide edge 45 for alignment with a major radius point withrespect to a center coinciding with the scribed center point 46.Adjacent the reference slot 44 is a minor axis slot 48 having a guideedge 50 to locate the minor radius. Between the reference slot 44 andthe slot 48 is an intermediate slot 52 having a guide edge 54, thepurpose of this particular guide edge being to locate a third pointbetween the major and minor radii, to provide the proper positioning ofthe curved edge 42, a minimum of three points being essential to definethe curve. The third point located by the intermediate guide edge 54should be on a radius from the common center at a convenient angle, suchas 30 or 45 degrees from the major axis, so that the intermediate axiscan easily be projected for accurate positioning of the point. In theconstruction of an isometric ellipse, this intermediate axis isrepresented by the isometric axis, which is always at 30 degrees to themajor axis, for instance. The template 40 is used in a manner similar tothat described above, the known radius being drawn and two other radiilocated therefrom by positioning the template and marking the points inthe guide slots.

By way of illustration, the guide slots 44, 48 and 52 are shown ascurved, but could be straight. Also, the intermediate slot 52 may bereplaced by a scribed guide line, as in the isometric template, or,conversely, the reference line 22 of the template may be a slot, eitherbeing suitable as a guide.

Some types of ellipse guides, such as the large sheets containingelliptical openings of various sizes, are limited to drawing specificsizes of ellipses. The template described herein, however, may be usedto draw ellipses of any size within the limits of the particulartemplate.

The operation of this invention will be clearly comprehended from aconsideration of the foregoing description of the mechanical detailsthereof, taken in connection with the drawing and the above recitedobjects.

4 It will be obvious that all said objects are amply achieved by thisinvention.

It is understood that minor variation from the form of the inventiondisclosed herein may be made without departure from the spirit and scopeof the invention, and that the specification and drawing are to beconsidered as merely illustrative rather than limiting.

I claim:

1. An ellipse drawing guide, comprising: a template of transparent flatsheet material having a curved edge of progressively varying radiuscorresponding to a composite curve of one quadrant of the ellipses inthe range of ellipses to be drawn; a reference center point marked onsaid template; a linear visual reference line marked on said templateand spaced from said center point; a pair of slots in saidtemplate; saidslots having guide edges spaced in relation to said reference line suchthat, along a line projected from said center point to intersect a givenpoint on said reference line, the distance from the center point to thereference line represents a known radius of the ellipse to be drawn andthe distances from the center point to said guide edges represent twoother radii of the ellipse.

2. An isometric ellipse drawing guide, comprising: a template oftransparent, flat sheet material having a curved edge of progressivelyvarying radius corresponding to a composite curve of one quadrant of therange of ellipses to be drawn; a reference center point marked on saidtemplate; a reference line marked on said template and spaced from saidcenter point; a pair of slots in said template on opposite sides of saidreference line; said slots having guide edges spaced with relation tosaid reference line such that, along a line projected from said centerpoint to intersect a given point on said reference line, the distancefrom the center point to the reference line rep resents the isometricradius and the distances from the center point to said guide edgesrepresent the major and minor radii of the ellipse to be drawn.

References Qited in the file of this patent UNITED STATES PATENTS2,499,935 Suto Mar. 7, 1950

